Method of rendering villous surfaces noncrocking



Aug. 25, 1942. c. l.. CAMPBELL METHOD OF RENDERING VILLOUS SURFACESANNCIIOCKIIXG Filed March 28, 1940 Patented Aug. 25, 1942 METHOD FRENDERING VILLOUS SUBFACES NONCBOCmG cantoni.. campbell, stemma; conn.,assigner to The Viscol Company, Stamford, Conn., a corporation ofConnecticut Application March 28, 1940, Serial-N0. 326,486

(Cl. Eil- 88) Claims.

.The invention relates to a method of treating flexible materials havinga villous or nap surface, and to the product resulting therefrom.

While the invention has particular utility when applied to the finishingof buied or suede leather, it is also applicable to other materialshaving a napped or hairy surface, such, for example, as articial ormutation suede leather, velvet, plush, or other pile fabrics, ormaterial on which the nap has been raised by special processes or hasbeen produced by the application of separate bres such as cotton orwwbolock, bufdng dust, etc. to the surface of the material.

In suede leather, as is well known, it is the iiesh side of the skinwhich is used to produce the finished surface. and this is buffed in amanner to produce a nap or villous surface comprising upstanding ibres.Such surface has a soft, velvety feel, which is one bf the desirablecharacteristics of this type of leather.

As is also well known in the art, it is frequently necessary to applysuitable pigments to buffed leather in order to level the color andotherwise improve the surface appearance. These pigments may .be appliedin either a wet or dry state and usually no binder or other means ofcausing them to adhere to the leather` is employed. The pigments merelybecome embedded in the hairs or bres.

Although the excess pigment is brushed od by suitable means, that whichremains has a tendency to rub off on and smudge or discolor clothing,upholstery and similar surfaces with which it may come in contact. Thiswell known defect of suede leather is called crocking In cases where theleatherY is dyed but not pigmented, as above mentioned, the bumng dustitself becomes embedded in the nap, and produces objectionable smudgingand discoloring of clothing and the like, in the same manner aspigments. f

Dust or particles of nely divided solid matter may also become embeddedin other materials having a villous surface, such as artificial leather,pile fabrics and the like, above mentioned.

It is the primary object of the present invention to provide means forlocking in this dust or finely divided matter so as to prevent it fromescaping` or coming out or rubbing oi, and to do this withoutdisadvantageously aiectlng the character or appearance of the material.

More specically, the object of the invention is to provide means foreliminating crocking,

and to produce a substantially non-cracking suede or bufied leather.

To this end.' the invention contemplates treating the villous surfacewith a thin illm produced -by applying a suitable liquid coatingcomposition. In carrying out this idea, however, the problem whichpresents itself is to produce a film or coating of such character thatit will not cause the fibres to mat or adhere to each other in groups, or produce other undesirable results. In the case of suede leather, theimportant thing is to avoid impairing the velvety feel" of the goods;

The essential characteristics of such a. lm or coating are, therefore,that it must not substantially alter the feel of the villous surface orthe flexibility of the material to which it is ap- Y plied; that it mustnot mat the fibres together; and that it must not disadvantageouslyalter the color of the goods.

In order to meet the above qualications, l find that the lm or coatingmaterial must not Aonly be exceptionally soft and pliable, when set andother villous surfaces such as described, the

ing of relatively smooth surfaces.

material must have such a low degree of adhesiveness that it will notcause the fibres to permanently adhere to each other. 'Ihe film producedby the use of such a non-adhesive coating composition clings to thevillous surface solely by virtue of the fact that the irregularly shapedfibres are surrounded by and/or embedded in such lm, and the film isthus mechanically anchored in position.

Suitable coating compositions for the present vpurpose may be preparedfrom a wide range of materials. They may be prepared from materialsheretofore deemed unsuitable for the usual coating compositions,.because of lack of adhe- Example No. 1 Parts by weight Rapeseed nil 100Sulphur chloride 121/2 Naphtha 90 The sulphur chloride is first mixedwith the oil and stirred, and as vulcanization proceeds and the mixturethickens, the naphtha is gradually added. When the reaction is complete,and the naphtha has all been added, a mixture results which should havea viscosity of about 2.2 (measured with an Engler viscosimeter) To twovolumes of the above concentrated mixture, I then add a relatively largeamount of solvent, amounting preferably to as much as thirty volumes.additional naphtha, but ispreferably a mixture of half naphtha and halfcarbon tetrachloride, which is less inflammable. The thus diluted liquidis then ready to apply to the suede leather or other villous surface byspraying by means of air pressure,

As another illustration, I may employ a mixture of partially vulcanizedoil with drying oils. I may employ the same vulcanized oil as in ExampleNo. 1, or I may use other vulcanizable oils such as cottonseed oil, as follows:

Parts by weight cottonseed nil 100 Sulphur Chloride 18 Naphtha 90 Thisis then mixed with drying oils and other materials. as follows:

Example No. 2

Parts byl weight Partially vulcanized oil solution (as above) 20China-wood oil 30 Linseed nil 30 Manganese dryer 6% solution' .125Solvent naphtha 800 The iirst three items, comprising the vulcanized anddrying oils, are thoroughly mixed together. the drier (which may be ofthe linoleate type) is dissolved in the naphtha, and the whole4 mixedtogether in an enclosed mixer.

The resulting solution is thin enough to be readily sprayed.

Instead of 30 parts each of China-wood oil an linseed oil, 60 parts. oflinseed oil may be used.

Similarly, any other suitable drying oil may be employed by slightlyvarying the proportions of drier and vulcanized oil, as necessary tosecure a proper balance.

It will be understood that in this example, the purpose of thevulcanized oil is to prevent the drying oils from forming a hard,adherent lm. The' presence of the vulcanized oil renders the nlmpermanently soft and pliable, and relatively non-adhesive.

This may consist entirely of Still another group of substances which maybe successfully employed comprise natural rubat the same time, does notresult in the production of any appreciable drag. In preparing such acomposition, I may use ingredients in the proportions shown below.

Example No. 3

. Pounds 45% V2 sec. nitro-cotton solution.. l5

Plasticized rubber 23 Toluol 640 Ethyl acetate 128 Butyl acetaha 128 Rawrubber, such as that known as pale crepe, is used, and thisis'masticated for a much longer period than is customary in rubbercompounding, for example, one and one-half hours, in order to reduce theviscosity of the resulting mixture.

After this ultra-mastication, the plasticized rubber is dissolved in amixture of the three solvents, by agitation in an enclosed mixer. Whenthe rubber is entirely in solution, thus forming a thin rubber cement,the nitro-cotton solution is added and agitation continued to insurethorough mixing. Although V2 sec. cotton is specified in the aboveexample, the exact viscosity of the cellulose derivative may vary overwide limits without materially affecting the results, provided anequivalent amount of dry cellulose derivative is employed in every case.Equally good results may be obtained by using nitro-cotton solutionswith viscosities ranging from V2 sec. to 60 sec.

'I'he essential thing in making up this coating composition is to employliquid mixtures which' are mutual solvents of the nitro-cotton and ofthe rubber.

` Many other solvents, such as commercial lac- (quer thinners, includingamyl acetate, or combinations thereof with other liquids such asalcohol, may be substituted for the solvent mixture specified, providedthat the least volatile ingredient is a common solvent of both rubberand the cellulose derivative, and provided also that the alcohol contentis sufficiently low so that the rubber will not be thrown out" ofsolution.

In order to provide additional coverage and to further level the colorof the villous surface, it is often desirable to incorporate in theabove coating compositions suitable pigments. These may be added in anywell known manner, as, for example, by grinding into the solutions thedesired quantity of pigment, preferably before unal dilution with thefull amount of solvents. No attempt is made to specify the preciseamount of pigment that should be added, because this will i depend onparticular circumstances and may vary adhesiveness, but the filmsresulting therefrom must have very slight; mechanical strength. Thus,for instance, the composition set forth in Example No. 1, if applied toa smooth surface as glass or sheet metal, will produce a. film, which,when dried or set, has practically no adhesiveness or mechanicalstrength. If such a nlm is rubbed with the finger, the material win rouup in noodlesf and rub off, while, if anattempt is made to lift an edgeof the nlm, as by means of a knife blade, and strip it from the smoothsurface, it will merely come to pieces in small lfragments, not havingsufficient strength to hold together. 'I'his characteristic of lowadhesiveness and small mechanical strength is also true of the other twoexamples.

The amount of the liquid coating composition and the purpose for whichthe :coating is applied.

Even in the Icase of suede leather, the amount of coating material touse depends on the kind of leather, the amount of builing, the amount ofdust or pigment embedded in the nap, etc. By way of illustration, it may.be said that the amount of coating material applied to the surface ofsuede leather, in carrying out the invention, may vary from .3 ounces to2 ounces per square foot. The proper amount for any particular kind andtype of surface being treated can only be determined by experiment.

The amount of liquid employed is usually sumcient to thoroughly wet thematerial and the liquid penetrates the nap and settles down throughoutthe mass of the nbres and around the dust or pigment, and when thesolvents have evaporate, there remains a Ipermanently soft, pliable nlm,covering and surrounding the nbres of irregular shape, and thusmechanically anchored to the material.

In order that the principle underlying the invention may be moreIclearly understood, refere ence is had to the accompanying drawing,forming rpart of this specification, and in which the figure is afragmentary transverse section on a greatly enlarged scale,` through thebuned side of a piece of suede leather treated in accordance with theinvention.

It will be understood that this drawing, which is a highly magninedview, is intended to illustrate more o r less conventionally anddiagrammatically .what happens when a piece of buifed or suede leatheris pigmented and coated in accordance with the :present invention.

In this drawing, a designates the portion of the main body of theleather adjacent the nesh side, while b designates the fibresconstituting the buifed or villous surface. It will be understood thatthese nbres are, in fact, made up of bundles of smaller nbrils ornlaments, some of which branch from the sides of the main group, asindicated at c, the outer ends of these branches, and also of the maingroup, being ragged and frayed, due to the cutting and tearing effectsof the bufnng operation. In other words, the surface comprising the nbregroups such as b and cis highly irregular.

To this irregular villous buifed surface is applied nnely dividedcoloring material or pigment. The particles of such pigment areindicated at d. Many of these particles nnd their way down into thespaces and pockets adjacent the roots or bases of the fibre groups,while others become embedded in and cling to the sides or endsof thenbre groups themselves, as indicated atd'.

When the coating material is applied to such e. bunedsurface, as byspraying, some of it covers the nbre groups, enveloping the pig-mentparticles clinging thereto, and some of it finds its 5 way down into thecrevices andpockets around the base of the nbre groups.

Thus a substantially continuous film is formed surrounding and coveringthe individual fibre groups and the particles of pigment which cling toor are embedded therein.

The thickness orf this film adjacent the base of the nbre groups isdetermined .by the amount of coating material which is applied. Thismaterial, however, Ibeing extremely nuent and relatively non-adhesive,tends to run-down the nbre groups and collect in the crevices andpockets around the bases thereof, so that the thickness of the nlm ewhich covers the outer portions of the nbre groups, remains practicallyconstant,

within limits, regardless of the amount of material applied. Asindicated in the drawing, the nlm e enclosing the outer portions of thenbre groups, remains relatively thin, whilevthe nlm e surrounding thelower portions of the nbre groups is relatively thicker, andthethickness of this \nlm e is determined |by the amount of coatingmaterial which is applied.

In practice, care must be exercised to avoid applying an excessiveamount of coating material such as would cause the nlm e to become toothick, and the crevices and spaces between the fibres nlled up to toogreat an extent. In other words, in order to preserve the velvet feel ofthe material, it is necessary to refrain from building up the nlm e toohigh and to maintain the outer portions of the nbre groups separate fromeach other, and free to move about, and,

owing to the thinness, softness and flexibility of It appears that inorder to have a soft fee1,4v

it is not necessarily a requirement that the ends of the fibre groups bebare, but merely that they be free from each other and nexible.

'In case a little too much of the liquid coating composition is appliedto the leather, so that there is a tendency for the nap to becomematted, thus giving rise to a somewhat harsh feeling,

it is only necessary to brush the leather lightly, after the lsolventhas evaporated. This results in restoring the feel and appearance to theleather surface, which effect is probably due to the fact that the endsof the nbres are broken loose or separated from each other.

In order to roughly illustrate the appearance of buffed leather coatedin accordance with the present invention, it may -be said that whathappens is somewhat similar to the effect of a light sleet storm on aplot of lawn grass, or in a still more highly magnined concept, theelect of a sleet storm on a. thickvforest of bare trees. The essentialdifference is,\however, that while, in the sleet storm, the applicationof additional matelrial continuously increases the thickness of thecoating on the twigs and branches, in the present invention theapplication of additional material appears not to substantially increasethe thickness of the coating on the trees and branches,

but the material collects in a layer of greater or less thickness aroundthe bottoms or bases.

While, in the claims, I have, for simplicity, used the term nbres, itwill be understood that I mean to include either single nbres or groupsof nbres as above explained. l

What I claim is:

1. A new product .comprising buffed leather, in the buffed surface ofwhich nely divided solid material is embedded, said material beingcovered by a protecting film which surrounds the individual fibres andis thus anchored to the buiedurface, the outer portion of said fibresbeing substantially free and separate and said nlm being of such 'asoft, flexible, non-adhesive nature that the velvet feel of the leatheris not substantially impaired thereby.

2. A new product comprising buied leather having a pigment embeddedtherein between the fibres thereof, and having a soft, pliable nlmapplied Vthereto over said pigment, and surrounding the bres, the outerends of said fibresremaining substantially free and separate, said nlmbeing relatively thick at the point where it surrounds the base of thefibres, and relatively thin at the point where it covers the outer endsof said libres. 3. A flexible sheet having a villous surface,

and having a soft, pliable. substantially continuous nlm comprisingvulcanized oil surrounding and interlocked with the base of the fibresthereof. the outer ends of said fibres being substantially separate fromeach other.

4. A flexible sheet having a villous surface, and having a soft, pliablesubstantially continuous lm of low adhesiveness containing a mixture ofvulcanized and drying oils surrounding and interlocked with the base ofthe ilbres thereof, the outer ends of said fibres being substantiallyfree and un-matted.

5. As a new product, sueded leather having iinely divided solid materialembedded in the builed surface thereof, and also having a soft,protecting lm of low adhesiveness and slight mechianical strengthenveloping said material .and the individual n bres of the leather, saidlm containing a vulcanized oil, and the outer portions of said fibresremaining'substantially free and separate.

6. As a new product, sueded leather having l finely divided solidmaterial embedded in the buied surface thereof, and also having anonsticky, soft, protecting film enveloping said material and theindividual fibres of the leather, said lm comprising a mixture of rawrubber and a cellulose derivative, and the outer ends of said fibresremaining substantially free and separate.

7. A new varticle of manufacture comprising non-crocking suede leather,said leather havin!V -the fibres thereof, the end portions of saidfibres being substantially free and separate from each other.

9. The method of locking in finely divided solid matter embedded in thebres of a flexible sheet having a villous surface which comprisesspraying onto said sheet a liquid coating material of such low viscositythat it flows along the fibres and collects at the base thereof, oversaid solid matter, thus forming, when dry, a substantially continuousillm covering said solid matter and surrounding and interlocked with thebases of the iibres, and so limiting the amount of such coating materialthus applied that the ends of the fibres are not caused to mat or clingtogeher, but remain substantially free and separa e. y

10. The method of rendering suede leather non-crocking which comprisesspraying on to the buffed surface thereof, in which finely divided solidmatter is embedded, a liquid coatingmaterial of such nature that itpenetrates the nap and collects around and at the base of the fibresover the finely divided solid matter embedded therein, thus forming,when dry, a film vcompletely covering said solid matter and enfeel isnot substantially impaired.

CLINTON L. CAMPBELL.

